1) Field of the Invention
The present invention relates to a cell using a film outer casing body for the cell case.
2) Description of the Prior Art
In recent years, there has been a rapid reduction in the size of mobile electronic devices such as mobile telephones and PDAs. Further reduction in thickness and weight is accordingly required of cells and batteries that serve as the driving power sources of such devices.
To meet this demand, light-weight thin cells have been developed utilizing, as the cell cases, film outer casing bodies made of a laminate film that is a lamination of resin and a metal foil such as aluminum.
The film outer casing bodies excel in thinness, flexibility, and lightness, but have the problem of easiness for deformation upon application of external force. External impacts can easily travel through the internal cell. Thus, the cells using the film outer casing bodies can be problematic in that the electrode body is easily damaged by the shock of, say, inadvertent drop, and that the damage of the electrode body often causes internal short-circuiting.